<!DOCTYPE html>
<html lang="en">
<head>
	<title>three.js webgl - materials - compressed textures</title>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
	<link type="text/css" rel="stylesheet" href="main.css">
</head>
<body>

<div id="info">
	<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> - webgl - compressed KTX textures<br />
	<a href="https://www.khronos.org/opengles/sdk/tools/KTX/file_format_spec/">Khronos Texture</a> is a lightweight file format for OpenGL
</div>

<script type="module">
	import * as THREE from '../build/three.module.js';

	import { KTXLoader } from './jsm/loaders/KTXLoader.js';

	/*
	This is how compressed textures are supposed to be used:

	best for desktop:
	BC1(DXT1) - opaque textures
	BC3(DXT5) - transparent textures with full alpha range

	best for iOS:
	PVR2, PVR4 - opaque textures or alpha

	best for Android:
	ETC1 - opaque textures
	ASTC_4x4, ASTC8x8 - transparent textures with full alpha range
	*/

	let camera, scene, renderer;
	const meshes = [];

	init();
	animate();

	function init() {

		renderer = new THREE.WebGLRenderer( { antialias: true } );
		renderer.setPixelRatio( window.devicePixelRatio );
		renderer.setSize( window.innerWidth, window.innerHeight );
		document.body.appendChild( renderer.domElement );

		const formats = {
			astc: renderer.extensions.has( 'WEBGL_compressed_texture_astc' ),
			etc1: renderer.extensions.has( 'WEBGL_compressed_texture_etc1' ),
			s3tc: renderer.extensions.has( 'WEBGL_compressed_texture_s3tc' ),
			pvrtc: renderer.extensions.has( 'WEBGL_compressed_texture_pvrtc' )
		};

		camera = new THREE.PerspectiveCamera( 50, window.innerWidth / window.innerHeight, 1, 2000 );
		camera.position.z = 1000;

		scene = new THREE.Scene();

		const geometry = new THREE.BoxGeometry( 200, 200, 200 );
		let material1, material2;

		// TODO: add cubemap support
		const loader = new KTXLoader();

		if ( formats.pvrtc ) {

			material1 = new THREE.MeshBasicMaterial( {
				map: loader.load( 'textures/compressed/disturb_PVR2bpp.ktx' )
			} );
			material2 = new THREE.MeshBasicMaterial( {
				map: loader.load( 'textures/compressed/lensflare_PVR4bpp.ktx' ),
				depthTest: false,
				transparent: true,
				side: THREE.DoubleSide
			} );

			meshes.push( new THREE.Mesh( geometry, material1 ) );
			meshes.push( new THREE.Mesh( geometry, material2 ) );

		}

		if ( formats.s3tc ) {

			material1 = new THREE.MeshBasicMaterial( {
				map: loader.load( 'textures/compressed/disturb_BC1.ktx' )
			} );
			material2 = new THREE.MeshBasicMaterial( {
				map: loader.load( 'textures/compressed/lensflare_BC3.ktx' ),
				depthTest: false,
				transparent: true,
				side: THREE.DoubleSide
			} );

			meshes.push( new THREE.Mesh( geometry, material1 ) );
			meshes.push( new THREE.Mesh( geometry, material2 ) );

		}

		if ( formats.etc1 ) {

			material1 = new THREE.MeshBasicMaterial( {
				map: loader.load( 'textures/compressed/disturb_ETC1.ktx' )
			} );

			meshes.push( new THREE.Mesh( geometry, material1 ) );

		}

		if ( formats.astc ) {

			material1 = new THREE.MeshBasicMaterial( {
				map: loader.load( 'textures/compressed/disturb_ASTC4x4.ktx' )
			} );
			material2 = new THREE.MeshBasicMaterial( {
				map: loader.load( 'textures/compressed/lensflare_ASTC8x8.ktx' ),
				depthTest: false,
				transparent: true,
				side: THREE.DoubleSide
			} );

			meshes.push( new THREE.Mesh( geometry, material1 ) );
			meshes.push( new THREE.Mesh( geometry, material2 ) );

		}

		let x = - meshes.length / 2 * 150;
		for ( let i = 0; i < meshes.length; ++ i, x += 300 ) {

			const mesh = meshes[ i ];
			mesh.position.x = x;
			mesh.position.y = 0;
			scene.add( mesh );

		}

		window.addEventListener( 'resize', onWindowResize );

	}

	function onWindowResize() {

		camera.aspect = window.innerWidth / window.innerHeight;
		camera.updateProjectionMatrix();

		renderer.setSize( window.innerWidth, window.innerHeight );

	}

	function animate() {

		requestAnimationFrame( animate );

		const time = Date.now() * 0.001;

		for ( let i = 0; i < meshes.length; i ++ ) {

			const mesh = meshes[ i ];
			mesh.rotation.x = time;
			mesh.rotation.y = time;

		}

		renderer.render( scene, camera );

	}

</script>

</body>
</html>
